1. Field of the Invention
The present invention relates to an optical apparatus such as an auto-focus camera, monitor camera, or the like, which has an automatic focus adjusting function.
2. Related Background Art
The focus detecting function represented by a camera or the like has advanced from a single, central detecting area to three- or five-point area, and its detecting range has broadened with respect to the photographing area. Such broad detecting range is achieved not only by an advanced detecting optical system but also by advanced microcomputers that control the function.
Multi-point detecting areas can effectively prevent a so-called "central out-of-focus" state, i.e., a state wherein the focus is adjusted not on the object but on the background. Furthermore, when an object in motion is to be photographed, the object can be prevented from falling outside the focus detecting area.
FIG. 14A shows a narrow, linear single range used as a focus detecting area B with respect to a photographing frame A. On the other hand, FIG. 14B shows broadened focus detecting areas, i.e., three focus detecting areas B set for the photographing frame A. In FIG. 14B, three detecting areas are added in a direction perpendicular to the detecting area shown in FIG. 14A.
Since the number of focus detecting areas is increased from one central point to three points, the focus need not always be adjusted on the object at the center of the photographing frame, and the degree of freedom in photographing is increased.
Upon further developing such multi-focus detecting areas, an area AF function in which the detecting area has a given two-dimensional area with respect to the photographing frame A (in fact, a large number of focus detecting areas are formed densely) is realized.